According to the heavily growing importance of renewable energy in global energy production on the one hand and of electric and hybrid drives for cars on the other, the development of sophisticated energy buffering and storing systems has become a crucial aspect. Whereas wind farms and solar energy plants produce a rapidly increasing share of electrical energy in a couple of developed countries, the buffering of the energy produced by such power plants and the smart management of future electrical power supply systems (“smart grids”) is, to a large extent, still unresolved. Likewise, the smart buffering and management of electrical energy is crucial for a significant market share and for an ecologically beneficial operation of electric cars on a broad scale. Such systems have to be tailored both to the typically discontinuous production or consumption of electrical energy and to the physico-chemical peculiarities and restraints of available battery systems.
In electronics and low-voltage systems, capacitors, and in particular electrolytic capacitors, have long been known as devices for storing energy. However, relatively low capacitances and, resulting therefrom, low energy storage capacities preclude capacitors from use in electrical energy supply systems. Recently, electrochemical double layer capacitors (EDLC), or supercapacitors, have been used in “energy smoothing” applications and momentary-load devices, and have further been used for energy-storage in vehicles and in smaller power-plant applications, like home solar energy systems.